#define INTERNAL_NULLABLE_ATTRIBUTES
#if NETSTANDARD2_0 ||  NETCOREAPP2_0 ||  NETCOREAPP2_1 ||  NETCOREAPP2_2 || NET45 || NET451 || NET452 || NET6 || NET461 || NET462 || NET47 || NET471 || NET472 || NET48

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
// This code was copied from https://raw.githubusercontent.com/dotnet/corefx/48363ac826ccf66fbe31a5dcb1dc2aab9a7dd768/src/Common/src/CoreLib/System/Diagnostics/CodeAnalysis/NullableAttributes.cs

namespace System.Diagnostics.CodeAnalysis;

/// <summary>Specifies that null is allowed as an input even if the corresponding type disallows it.</summary>
[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class AllowNullAttribute : Attribute;

/// <summary>Specifies that null is disallowed as an input even if the corresponding type allows it.</summary>
[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class DisallowNullAttribute : Attribute;

/// <summary>Specifies that an output may be null even if the corresponding type disallows it.</summary>
[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class MaybeNullAttribute : Attribute;

/// <summary>Specifies that an output will not be null even if the corresponding type allows it.</summary>
[AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class NotNullAttribute : Attribute;

/// <summary>Specifies that when a method returns <see cref="ReturnValue"/>, the parameter may be null even if the corresponding type disallows it.</summary>
[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class MaybeNullWhenAttribute : Attribute
{
    /// <summary>Initializes the attribute with the specified return value condition.</summary>
    /// <param name="returnValue">
    /// The return value condition. If the method returns this value, the associated parameter may be null.
    /// </param>
    public MaybeNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;

    /// <summary>Gets the return value condition.</summary>
    public bool ReturnValue { get; }
}

/// <summary>Specifies that when a method returns <see cref="ReturnValue"/>, the parameter will not be null even if the corresponding type allows it.</summary>
[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class NotNullWhenAttribute : Attribute
{
    /// <summary>Initializes the attribute with the specified return value condition.</summary>
    /// <param name="returnValue">
    /// The return value condition. If the method returns this value, the associated parameter will not be null.
    /// </param>
    public NotNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;

    /// <summary>Gets the return value condition.</summary>
    public bool ReturnValue { get; }
}

/// <summary>Specifies that the output will be non-null if the named parameter is non-null.</summary>
[AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, AllowMultiple = true, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class NotNullIfNotNullAttribute : Attribute
{
    /// <summary>Initializes the attribute with the associated parameter name.</summary>
    /// <param name="parameterName">
    /// The associated parameter name.  The output will be non-null if the argument to the parameter specified is non-null.
    /// </param>
    public NotNullIfNotNullAttribute(string parameterName) => ParameterName = parameterName;

    /// <summary>Gets the associated parameter name.</summary>
    public string ParameterName { get; }
}

/// <summary>Applied to a method that will never return under any circumstance.</summary>
[AttributeUsage(AttributeTargets.Method, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class DoesNotReturnAttribute : Attribute;

/// <summary>Specifies that the method will not return if the associated Boolean parameter is passed the specified value.</summary>
[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
#if INTERNAL_NULLABLE_ATTRIBUTES
internal
#else
public
#endif
    sealed class DoesNotReturnIfAttribute : Attribute
{
    /// <summary>Initializes the attribute with the specified parameter value.</summary>
    /// /// <param name="parameterValue">
    /// The condition parameter value. Code after the method will be considered unreachable by diagnostics if the argument to
    /// the associated parameter matches this value.
    /// </param>
    public DoesNotReturnIfAttribute(bool parameterValue) => ParameterValue = parameterValue;

    /// <summary>Gets the condition parameter value.</summary>
    public bool ParameterValue { get; }
}

#endif
